Arthroscopic-Assisted Treatment of Distal Radius Fractures

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CHAPTER 20 Arthroscopic-Assisted Treatment of Distal Radius Fractures

Sidney M. Jacoby, MD, Osterman A. Lee, MD

The advent of wrist arthroscopy in the early 1990s marked the beginning of a novel and valuable adjunct in the treatment of distal radius fractures.¹ Anatomical reduction, stable internal fixation, and preservation of soft tissues are cornerstone concepts in fracture reconstruction. Distal radius fractures represent a unique subset of upper extremity injuries because they often involve not only articular margins but also surrounding soft tissue structures critical to normal wrist function. As arthroscopic technology has evolved at a rapid pace, so, too, has the utility of wrist arthroscopy in the treatment of various subtypes of distal radius fractures.

Arthroscopic-assisted reduction/internal fixation (ARIF) provides a unique, magnified and illuminated view of the distal radial joint surface that allows precise reduction of fracture fragments. Comminuted fractures involving the distal articular surface are particularly difficult to manage because they have an inherent tendency toward instability, either by shortening or collapse, and are less amenable to closed manipulation and casting. Arthroscopy allows the surgeon to explore the biconcave distal radius articular surface and remove chondral defects, loose bodies, and fracture fragments in both the radiocarpal and distal radioulnar joints. In addition to assisting with percutaneous pinning, external fixation, or limited open reduction techniques, arthroscopic visualization and repair of associated intercarpal soft tissue injuries is a crucial component to improving outcomes.

Precise reduction of the distal radial articular surface is critical in preventing the late sequelae of post-traumatic arthrosis. Numerous studies have shown that a poor result is likely if more than 1 mm of articular incongruity is present at the radiocarpal joint (Figs. 20-1 to 20-3).²^–⁶ Subchondral hematomas in the radiocarpal joint have also been shown to cause the early onset of mild osteoarthritis and worse outcomes after 1 year, even without a fracture line as demonstrated by arthroscopy.⁷ Arthroscopic irrigation and débridement of hematoma may therefore ultimately improve outcome by removing a possible impetus for early post-traumatic degenerative changes.

FIGURE 20-1 Anteroposterior (A) and oblique (B) radiographs of a distal radius fracture with more than a 2-mm articular incongruity results in traumatic arthritis.

FIGURE 20-2 Radiograph of distal radius fracture with more than 2-mm radial ulnar diastasis.

FIGURE 20-3 Radiograph of distal radius fracture with more than 2-mm dorsal volar diastasis.

ARIF affords a well-lit, magnified view of the distal radial joint surface with minimal morbidity. It has been shown to be superior to C-arm and plain radiographs for assessing both displacement between articular fragments as well as the diagnosis of soft tissue lesions.^8,⁹ In a study performed by Edwards and coworkers of intra-articular distal radial fractures that underwent closed manipulation and percutaneous pinning followed by sequential assessment of reduction by C-arm, radiography, and wrist arthroscopy, 33% of cases judged to have had optimal reduction by C-arm and radiography were found to have an articular displacement of more than 1 mm by adjunctive arthroscopy.⁸ It has also been shown that arthroscopic-assisted reduction and external fixation of distal radius fractures permits a more thorough inspection of the ulnar-sided components of the injury when compared with fluoroscopic-assisted reduction and external fixation of distal radius fractures alone. In addition, a prospective cohort study showed that at follow-up examination, patients who underwent arthroscopic-assisted procedures had a greater degree of supination, flexion, and extension than patients undergoing fluoroscopic-assisted surgery.¹⁰ It is now recognized that intraoperative fluoroscopic imaging does not provide sufficient precision to visualize a 1-mm step-off in the radial articular surface despite often satisfactory postoperative radiographs.^1,¹¹

Indications and Contraindications

Although the main indication for ARIF of a distal radius fracture is an intra-articular step-off of more than 1 mm, arthroscopy is particularly useful in the management of unstable or displaced intra-articular fractures as well as comminuted articular fractures. Additional fracture patterns amenable to ARIF include radial styloid fractures, lunate die-punch fractures, three-part T fractures, and Melone four-part fractures.¹² Other reasons to perform arthroscopy may include radiographic signs of concomitant injury, including diastasis of intercarpal joint spaces, subluxation of the distal radioulnar joint (DRUJ), or a broken carpal arch. ARIF may be contraindicated in the setting of forearm compartment syndrome, untreated median nerve compression, severe soft tissue injury, open joint injuries, unreduced carpal dislocations, infection, and complex regional pain syndrome.¹³

Timing of Surgery, Setup, and Portals

ARIF can be performed under either axillary block or general anesthesia between 3 and 7 days after the index traumatic event. Waiting a few days allows the surgeon to avoid difficulty with visualization secondary to active bleeding. Conversely, if arthroscopy is performed after 7 days, the fracture begins to consolidate and manipulation of the fragments is more challenging.

Before introducing the arthroscope, a pneumatic tourniquet (set at 250 mm Hg) is applied to the upper arm and an Esmarch bandage is wrapped around the forearm to diminish fluid extravasation into the muscle compartments. Lactated Ringer’s solution is used for irrigation because of its rapid absorbability.¹⁴

The operating room setup and arthroscopic portals are virtually identical to those used in an elective wrist arthroscopy. Either a horizontal or a vertical arthroscopic setup may be used (Fig. 20-4).¹⁵ Swelling often makes it difficult to palpate the extensor intervals, so the use of bony landmarks including the bases of the second and third metacarpals, Lister’s tubercle, radial styloid, and distal ulna is useful. Traction provides ligamentotaxis, which aids in fracture fragment reduction. A useful technique to avoid iatrogenic cartilage damage during the introduction of arthroscopic instrumentation is the use of a 20-gauge needle in the proposed 3-4 portal before making a skin incision.¹⁴ If the needle passes unobstructed without engaging bone, the portal is likely in the correct position. Fluoroscopy can also aid in needle placement and portal establishment.

FIGURE 20-4 Setup for arthroscopic-assisted internal fixation. Note vertical traction tower, arthroscope, and C-arm fluoroscopy.

The arthroscopic sheath is usually introduced in the 3-4 portal, and an outflow cannula is established in the 6-R portal. The first image obtained on entry into the joint is usually that of fibrin clot and debris. Lavage is particularly useful and nearly always necessary to clear the joint and provide unobstructed visualization for precise fragment manipulation and reduction. Washing out fracture hematoma and debris may also contribute to the increased range of motion and functional outcome associated with ARIF.^16,¹⁷

Midcarpal arthroscopy offers significant information to the arthroscopic examination, particularly in the setting of soft tissue injuries suspected with distal radius fractures. Hofmeister and associates showed that a pathological process leading to additional surgical intervention was found on midcarpal examination in more than 60% of patients undergoing arthroscopy for evaluation of soft tissue injuries in the setting of distal radius fractures.¹⁸

Surgical Technique

Distal radius fracture fragments are sometimes reduced with longitudinal traction and external manipulation alone. However, depressed and displaced fragments often require mobilization with either a probe in the joint or instruments such as a Freer elevator placed through a separate skin incision over the fracture. Kirschner wires (K-wires) are also extremely useful because they may be placed in fracture fragments, and, under arthroscopic guidance, depressed fragments may be elevated and realigned via a joystick type maneuver. Once the fracture fragments are appropriately reduced, the surgeon may visualize the articular surfaces with the unparalleled view afforded by the arthroscope.

Two-Part Radial Styloid Fractures

Most radial styloid fractures can also be reduced by closed manipulation. Adequate reduction may be evaluated fluoroscopically, arthroscopically, or by a combination of the two (Figs. 20-5 to 20-8). Because radial styloid fractures have a propensity for rotation, K-wire joysticks can be used to manipulate fracture segments. The K-wires may be inserted through a 14-gauge needle, drill sleeve, or drill tap to protect the surrounding neurovascular structures (radial artery and superficial branch of the radial nerve). Arthroscopic assessment of adequate reduction of the articular surface is best evaluated by placing the scope in the 4-5 portal. Once adequate reduction is obtained, the K-wires may be driven across the fracture or another means of fixation, such as a cannulated screw, may be used for fixation (Fig. 20-9). Arthroscopic assistance is also useful in assessing for associated soft tissue injuries in the setting of radial styloid fractures. Scapholunate tears have been identified in up to 50% of radial styloid fractures, and arthroscopic assistance is therefore useful in assessing for these intercarpal injuries.¹⁵